In late 2006, scientists in France published the recreation of another virus. This virus, named Phoenix by its creators, is a human endogenous retrovirus (HERV) estimated to be 5 million years old. HERVs are retroviruses able to infect human cells and insert copies of their genome into them. If this occurs in germ cells, the incorporated genome is passed on to following generations. It is estimated that about 8% of the human genome comes from copies of HERVs that have incorporated over millions of years, and may have a role in tumor formation and cancer. The experiments were cleared by the Commission de Genie Genetique, the authority in France which regulates the handling of genetically modified organisms in research institutions. In addition, all of the experiments were completed in a BSL-3 lab and Phoenix was modified so that it could only replicate once. Despite the fact that Phoenix has extremely low transmissibility, some in the scientific community question the wisdom both of bringing the ancient retrovirus back to life as well as doing so under less than BSL-4 conditions.